The present invention relates to an improved delivery system for the administration of large-molecule pharmaceuticals, e.g. peptidic drugs, vaccines and hormones. In particular it relates to pharmaceuticals which may be administered through the oral and nasal membranes.
In spite of significant efforts in academic and commercial laboratories, major breakthroughs in oral peptide and protein formulation have not been achieved. Relatively little progress has been made in reaching the target of safe and effective oral formulations for peptides and proteins. The major barriers to developing oral formulations for proteins and peptides include poor intrinsic permeability, lumenal and cellular enzymatic degradation, rapid clearance, and chemical stability in the gastrointestinal (GI) tract. Pharmaceutical approaches to address these barriers, which have been successful with traditional small, organic drug molecules, have not readily translated into effective peptide and protein formulations. Although the challenges are significant, the potential therapeutic benefits remain high especially in the field of diabetes treatment using insulin.
Scientists have explored various administration routes other than the injection for proteins and peptides. These routes include oral, intranasal, rectal, vaginal cavities for the effective delivery of large molecules. Out of the above four mentioned routes oral and nasal cavities have been of greatest interest to scientists. Both the oral and nasal membranes offer advantages over other routes of administration. For example, drugs administered through these membranes have a rapid onset of action, provide therapeutic plasma levels, avoid first pass effect of hepatic metabolism, and avoid exposure of the drug to hostile GI environment. Additional advantages include easy access to the membrane sites so that the drug can be applied, localized and removed easily. Further, there is a good potential for prolonged delivery of large molecules through these membranes.
The oral routes have received far more attention than has the other routes. The sublingual mucosa includes the membrane of ventral surface of the tongue and the floor of the mouth whereas the buccal mucosa constitutes the lining of the cheek. The sublingual mucosa is relatively permeable thus giving rapid absorption and acceptable bioavailability of many drugs. Further, the sublingual mucosa is convenient, acceptable and easily accessible. This route has been investigated clinically for the delivery of a substantial number of drugs. The ability of molecules to permeate through the oral mucosa appears to be related to molecular size, lipid solubility and peptide protein ionization. Small molecules, less than 1000 daltons appear to cross mucosa rapidly. As molecular size increases, the permeability decreases rapidly. Lipid soluble compounds are more permeable than non-lipid soluble molecules. Maximum absorption occurs when molecules are un-ionized or neutral in electrical charges. Therefore charged molecules present the biggest challenges to absorption through the oral mucosae.
Most proteinic drug molecules are extremely large molecules with molecular weight exceeding 6000 daltons. These. large molecules have very poor lipid solubility and are practically impermeable. Substances that facilitate the absorption or transport of large molecules ( greater than 2000 daltons) across biological membranes are known as the enhancers, (Lee et al., Critical Reviews in Therapeutic drug Carrier Systems, 8, 91, 1991; Lee et al., Critical Reviews in Therapeutic drug Carrier Systems, 8, 115, 1991, 1992). Enhancers may be characterized as chelators, bile salts, fatty acids, synthetic hydrophillic and hydrophobic compounds, and biodegradable polymeric compounds.
Various mechanisms of action of enhancers have been proposed. These mechanisms of action, at least for protein and peptidic drugs include (1) reducing viscosity and/or elasticity of mucous layer, (2) facilitating transcellular transport by increasing the fluidity of the lipid bilayer of membranes, and (3) increasing the thermodynamic activity of drugs (Critical Rev, 117-125, 1991, 1992).
Many enhancers have been tested so far and some have found to be effective in facilitating mucosal administration of large molecule drugs. However, hardly any penetration enhancing products have reached the market place. Reasons for this include lack of a satisfactory safety profile respecting irritation, lowering of the barrier function, and impairment of the mucocilliary clearance protective mechanism. The main factor to be considered in the use of enhancers especially related to bile salts, and some protein solubilizing agents is extremely bitter and unpleasant taste. This makes their use almost impossible for human consumption on a daily basis. Several approaches were utilized to improve the taste of the bile salts based delivery systems, but none one of them are commercially acceptable for human consumption to date. Among the approaches utilized includes patch for buccal mucosa, bilayer tablets, controlled release tablets, use of protease inhibitors, buccally administered film patch devices, and various polymer matrices.
The basic problem associated with the above technologies is the use of large quantities of bile acids and their salts to promote the transport of the large molecules through membranes in the form of localized delivery system using patches or tablets. In spite of using protease inhibitors and polymer coatings the technologies failed to deliver proteinic drugs in the required therapeutic concentrations. Further, the problem is compounded because of the localized site effect of the patch which resulted in severe tissue damage in the mouth. Most attempts were made to deliver large molecules via the oral, nasal, rectal, and vaginal routes using single bile acids or enhancing agents in combination with protease inhibitors and biodegradable polymeric materials. However, it is extremely difficult to achieve therapeutic levels of proteinic drugs using these formulations. As single enhancing agents fails to loosen tight cellular junctions in the oral, nasal, rectal and vaginal cavities for a required period of time to allow passage of large molecules through the mucosal membranes without further degradation. This problem makes it impractical to use the above mentioned systems for a commercial purpose. In order to overcome the above mentioned problem of the bitter taste, irritation and the penetration of large molecules through the sublingual, buccal and GI tract mucosal lining, a system has now been designed where protein drug was encapsulated in mixed micelles made up of combination of enhancers, e.g. yolk proteins (lecithins). This system allows opening of the paracellular junctions (tight junctions) in oral as well as in GI tract by gI motility movement with high degree of protease activity preserved and protecting molecules from premature degradation in the hostile acidic and proteolytic GI environment.
It is believed that the mixed micelles encapsulate molecules with high degree of efficiency ( greater than 90% encapsulation). These mixed micelles are extremely small in the size (1 nm to 10 nm), and are smaller than the pores of the membranes in the oral cavity or the GI tract. It is therefore believed that the extremely small size of mixed micelles helps encapsulated molecules penetrate efficiently through the mucosal membranes of the oral cavity.
The absorption of proteins and peptides is believed to be enhanced by the diffusion of large molecules entrapped in the mixed micellar form through the aqueous pores and the cell structure perturbation of the tight paracellular junctions.
The amount of physiologically peptide or protein in the compositions of this invention is typically a quantity that provides an effective amount of the drug to produce the physiological activity (therapeutic plasma level) for which peptide or protein is being administered. In consideration of the fact that the bioavailability of any active substance can never be 100%, that is to say the administered dose of the active drug is not completely absorbed, it is preferable to incorporate slightly larger amount than the desired dosage. Where the dosage form is a spray (aerosol) or the like which is repeatedly dispensed from the same container, it is recommendably so arranged that the unit dose will be slightly greater than the desired dose. It should be understood that dosage should vary with species of warm blood animals such as man, domestic animals, and their body weights. Although the composition of this invention is prepared as the microfine droplets (1 to 10 nm or less) by the virtue of its preparation methods used and suitable combinations of enhancer compound characteristics. The utilization of atomizer or aerosol spray devices (metered dose inhalers or nebulizers) may be useful to further a sufficient reduction of particle size for effective inhalation from the nasal or oral cavity so the drug may successfully absorbed or reach to the specific site.
The therapeutic composition of the present invention can be stored at room temperature or at cold temperature. Storage of proteinic drugs is preferable at the cold temperature to prevent the degradation of the drugs and to extend their shelf life. While the mixed micellar therapeutic composition of the invention is applied to the mucosal membranes, the sites of administration may the same as those used for the usual mucosal therapeutic preparation. Generally, oral, transdermal and nasal are the favourite sites of the administration but the composition can be applied to the rectal and vaginal mucosa. According to the physiologically active peptide or protein used, the dosage form and the site of administration, a specific administration method can be selected.
As used herein, the term xe2x80x9cedetatexe2x80x9d is used herein to refer to pharmaceutically acceptable salts of ethylenediaminetetraacetic acid.
Accordingly the present invention provides a mixed micellar pharmaceutical formulation, having a pH of between 6.0 and 7.0 comprising a proteinic pharmaceutical agent in micellar form, water, an alkali metal lauryl sulphate in a concentration of from 1 to 10 wt./wt. % of the total formulation, a pharmaceutically acceptable edetate in a concentration of from 1 to 10 wt./wt. % of the total formulation, at least one alkali metal salicylate in a concentration of from 1 to 10 wt./wt. % of the total formulation, and at least one micelle forming compound selected from the group consisting of lecithin, hyaluronic acid, pharmaceutically acceptable salts of hyaluronic acid, octylphenoxypolyethoxyethanol, glycolic acid, lactic acid, chamomile extract, cucumber extract, oleic acid, linolenic acid, borage oil, evening of primrose oil, trihydroxy oxo cholanylglycine, glycerin, polyglycerin, lysine, polylysine, triolein and mixtures thereof, wherein the amount of each absorption enhancing compound is present in a concentration of from 1 to 10 wt./wt. % of the total formulation, and the total concentration of absorption enhancing compounds are less than 50 wt./wt. % of the formulation.
In an embodiment, the alkali metal lauryl sulphate, the edetate and the alkali metal salicylate are each in a concentration of from 2 to 5 wt./wt. % of the total formulation.
In one embodiment, the edetate is an alkali metal edetate. Preferably the alkali metal edetate is be selected from the group consisting of disodium edetate, dipotassium edetate, and combinations thereof. In another embodiment, the alkali metal lauryl sulphate is sodium lauryl sulphate.
In a further embodiment, the alkali metal salicylate is sodium salicylate.
In another embodiment, the lecithin is selected from the group consisting of Phospholipon-H (trade mark) saturated phospholipid, Phospholipon-G (trade mark) unsaturated phospholipid, phosphatidylcholine, phosphatidyl serine, sphingomyelin, phosphatidylethanolamine, cephalin, and lysolecithin.
In one embodiment, one of the absorption enhancing compounds is selected from the group consisting of hyaluronic acid, pharmaceutically acceptable salts of hyaluronic acid and mixtures thereof, the concentration such micelle forming compound being from about 1 to about 5 wt./wt. %.
In another embodiment, suitable for delivery through nasal passages, mixed micellar pharmaceutical formulation is suitably diluted to avoid irritation of the nasal passages.
For insulin-containing and some other compositions, the composition may also contains at least one inorganic salt which opens channels in the gastrointestinal tract and may provide additional stimulation to release insulin. Non-limiting examples of inorganic salts are sodium, potassium, calcium and zinc salts, especially sodium chloride, potassium chloride, calcium chloride, zinc chloride and sodium bicarbonate.
It will be recognized by those skilled in the art that for many pharmaceutical compositions it is usual to add at least one antioxidant to prevent degradation and oxidation of the pharmaceutically active ingredients. It will also be understood by those skilled in the art that colorants, flavouring agents and non-therapeutic amounts of other compounds may be included in the formulation. Typical flavouring agents are menthol and sorbitol.
In one embodiment the antioxidant is selected from the group consisting of tocopherol, deteroxime mesylate, methyl paraben, ethyl paraben and ascorbic acid and mixtures thereof. A preferred antioxidant is tocopherol.
In a preferred embodiment at least one protease inhibitor is added to the formulation to inhibit degradation of the pharmaceutical agent by the action of proteolytic enzymes. Of the known protease inhibitors, most are effective at concentrations of from 1 to 3 wt./wt. % of the formulation.
Non-limiting examples of effective protease inhibitors are bacitracin, soyabean trypsin, aprotinin and bacitracin derivatives, e.g. bacitracin methylene disalicylate. Bacitracin is the most effective of those named when used in concentrations of from 1.5 to 2 wt./wt. %. Soyabean trypsin and aprotinin two may be used in concentrations of about 1 to 2 wt./wt. % of the formulation.
The formulation suitable for delivery through oral mucosal membranes may be in chewable form, in which case it will be necessary to add ingredients suitable for such form. Such ingredients include guar gum, powdered acacia, carrageenin, beeswax and xanthan gum.
The proteinic pharmaceutical agent may be selected from a wide variety of macromolecular agents, depending on the disorder being treated, generally with molecular weights greater than about 1000 and especially between about 1000 and 2 000 000. Preferred pharmaceutical agents are selected from the group consisting of insulin, heparin, low molecular weight heparin, hirulog, hirugen, huridine, interferons, interleukins, cytokins, mono and polyclonal antibodies, immunoglobins, chemotherapeutic agents, vaccines, glycoproteins, bacterial toxoids, hormones, calcitonins, insulin like growth factors (IGF), glucagon like peptides (GLP-1), large molecule antibiotics, protein based thrombolytic compounds, platelet inhibitors, DNA, RNA, gene therapeutics and antisense oligonucleotides.
The present invention also provides a process for making a pharmaceutical composition suitable for delivery through transdermal membranes comprising:
a) preparing a proteinic pharmaceutical agent composition in micellar form in an aqueous medium which has an alkali metal salicylate in a concentration of from 1 to 10 wt./wt. % of the aqueous micellar pharmaceutical agent composition, an alkali metal lauryl sulphate in a concentration of from 1 to 10 wt./wt. % of the aqueous micellar pharmaceutical agent composition and a pharmaceutically acceptable edetate in a concentration of from 1 to 10 wt./wt. % of the aqueous micellar pharmaceutical agent composition;
b) slowly adding the micellar proteinic pharmaceutical agent composition to at least one of the absorption enhancing compounds selected from the group consisting of lecithin, hyaluronic acid, pharmaceutically acceptable salts of hyaluronic acid, octylphenoxypolyethoxyethanol, glycolic acid, lactic acid, chamomile extract, cucumber extract, oleic acid, linolenic acid, borage oil, evening of primrose oil, trihydroxy oxo cholanylglycine, glycerin, polyglycerin, lysine, polylysine, triolein and mixtures thereof, while mixing vigorously, to form a mixed micellar composition; wherein the amount of the absorption enhancing compounds are each present in a concentration of from 1 to 10 wt./wt. % of the total formulation, and the total concentration of alkali metal salicylate, alkali metal lauryl sulphate, edetate and absorption enhancing compounds is less than 50 wt./wt. % of the formulation.
In one embodiment, the process provides an additional step of adding, while continuing vigorous mixing, at least one absorption enhancing compound different from that added in step b), selected from the group consisting of lecithin, hyaluronic acid, pharmaceutically acceptable salts of hyaluronic acid, octylphenoxypolyethoxyethanol, glycolic acid, lactic acid, chamomile extract, cucumber extract, oleic acid, linolenic acid, borage oil, evening of primrose oil, trihydroxy oxo cholanylglycine, glycerin, polyglycerin, lysine, polylysine, triolein and mixtures thereof.
In one embodiment the alkali metal lauryl sulphate is sodium lauryl sulphate.
In another embodiment the alkali metal salicylate is sodium salicylate.
In a further embodiment the alkali metal edetate may be selected from the group consisting of disodium edetate and dipotassium edetate.
In yet another embodiment, the formulation has a combinations selected from the group consisting of sodium hyaluronate and Phospholipon-H, ii) Phospholipon-H and glycolic acid, and iii) sodium hyaluronate and lecithin.
The vigorous mixing may be accomplished using high speed stirrers. The vigorous mixing may be accomplished by using high speed stirrers, e.g. magnetic stirrers or propellor stirrers, or by sonication.
In one embodiment, the mixed micellar formulation is formed by sonication of the aqueous micellar pharmaceutical agent composition in the presence of lecithin.
The present invention provides an improved method for delivery of macromolecular (high molecular weight) pharmaceutical agents, particularly through the membranes in the nose, mouth, vagina or rectum. The preferred delivery is through oral and nasal cavities. The pharmaceutical agents cover a wide spectrum of agents, including proteins, peptides, hormones, vaccines and drugs. The molecular weights of the macromolecular pharmaceutical agents are preferably above 1000, especially between 1000 and 2 000 000.
For example, hormones which may be administered with the present invention include thyroids, androgens, estrogens, prostaglandins, somatotropins, gonadotropins, erythropoetin, interferons, interleukins, steroids and cytokins. Vaccines which may be administered with the present invention include bacterial and viral vaccines such as vaccines for hepatitis, influenza, tuberculosis, canary pox, chicken pox, measles, mumps, rubella, pneumonia, BCG, HIV and AIDS. Bacterial toxoids which may be administered using the present invention include diphtheria, tetanus, pseudonomas and mycobactrium tuberculosis. Examples of specific cardiovascular or thromobolytic agents include heparin, hirugen, hirulos and hirudine. Large molecules usefully administered with the present invention include monoclonal antibodies, polyclonal antibodies and immunoglobins.
As will be understood, the concentration of the pharmaceutical agent is an amount sufficient to be effective in treating or preventing a disorder or to regulate a physiological condition in an animal or human. The concentration or amount of pharmaceutical agent administered will depend on the parameters determined for the agent and the method of administration, e.g. oral, nasal. For example, nasal formulations tend to require much lower concentrations of some ingredients in order to avoid irritation or burning of the nasal passages. It is sometimes desirable to dilute an oral formulation up to 10-100 times in order to provide a suitable nasal formulation.
The mixed micellar formulation is prepared by first preparing a first micellar composition which contains the pharmaceutically active agents, akali metal lauryl sulphate, edetate and alkali metal salicylate. For those compositions intended for administration through the nasal, oral, vaginal or rectal cavities, the first micellar composition is then added to at least one of the absorption enhancing compounds to form a mixed micellar composition. At least one other absorption enhancing compound may also be added subsequently. Preferably the first absorption enhancing compound is lecithin.
Although the present invention has such wide applicability, the invention is described hereinafter with particular reference to insulin and its analogues, which are used for the treatment of diabetes.
As indicated hereinbefore, the compositions of the present invention require that the pharmaceutical formulation be in mixed micellar form.
In the case of insulin, which is intended for administration through nasal or oral cavities, the first micellar solution may be made by adding a buffer solution to powdered insulin, and then stirring until the powder is dissolved and a clear solution is obtained. A typical buffer solution is an aqueous solution of sodium salicylate and sodium lauryl sulphate and disodium edetate. Typical concentration of sodium salicylate and sodium lauryl sulphate in the aqueous solution are about 3 to 20 wt./wt. % of each compound in the solution. Typically, insulin is present in the micellar solution in an amount which will give a concentration of about 2 to 4 wt./wt. % of the final formulation. Typically the concentration may be about 10 wt./wt. % of the first micellar composition.
The micellar solution is then added slowly to the first absorption enhancing compound, e.g. lecithin while mixing vigorously, e.g. sonicating, to form a mixed micelle liposomal solution. At least one other absorption enhancing compounds selected from the group consisting of lecithin, hyaluronic acid, pharmaceutically acceptable salts of hyaluronic acid, octylphenoxypolyethoxyethanol, glycolic acid, lactic acid, chamomile extract, cucumber extract, oleic acid, linolenic acid, borage oil, evening of primrose oil, trihydroxy oxo cholanylglycine, glycerin, polyglycerin, lysine, polylysine, triolein is then added. The mixing may be done with a high speed mixer or sonicator to ensure uniform micelle particle size distribution within the formulation.
Each of the absorption enhancing compounds, when present, is in a concentration of from 1 to 10 wt./wt. % of the total formulation.
Preferred salts of hyaluronic acid are alkali metal hyaluronates, alkaline earth hyaluronates and aluminium hyaluronate. The preferred salt is sodium hyaluronate. The preferred concentration of hyaluronic acid or pharmaceutically acceptable salts of hyaluronic acid is from 1 to 5 wt./wt. % of the total formulation. An even more preferred range is from 1.5 to 3.5 wt./wt. % of the total formulation.
Other ingredients may be added to the mixed micellar solution. For example, flavouring agents, antioxidants, salts, protease inhibitors or other pharmaceutically acceptable compound may be added.
In general the size of the micelle particles in the solution is about 1 to 10 nm, and preferably from 1 to 5 nm. Such a size distribution ensures effective absorption of the formulation, and therefore the pharmaceutical agent, through the membranes, for example the membranes in the oral and nasal cavities.
The specific concentrations of the essential ingredients can be determined by relatively straightforward experimentation. For absorption through the nasal and oral cavities, it is often desirable to increase, e.g. double or triple, the dosage which is normally required through injection of administration through the gastrointestinal tract.
As will be understood, the amount of each component of the formulation will vary depending on the pharmaceutical agent and the site of application. Preferred formulations oral or nasal application have the following combinations: i) sodium lauryl sulphate, sodium salicylate, disodium edetate, Phospholipon-H and sodium hyaluronate; ii) sodium lauryl sulphate, sodium salicylate, disodium edetate, lecithin and sodium hyaluronate; iii) sodium lauryl sulphate, sodium salicylate, disodium edetate, sodium hyaluronate and evening of primrose oil; iv) sodium lauryl sulphate, sodium salicylate, disodium edetate, Phospholipon-H and bacitracin; v) sodium lauryl sulphate, sodium salicylate, disodium edetate, Phospholipon-H, sodium hyaluronate and bacitracin; and vi) sodium lauryl sulphate, sodium salicylate, disodium edetate, sodium hyaluronate, oleic acid and gamma linoleic acid.
The therapeutic compositions of the present invention may be stored at room temperature or at cold temperature. Storage of proteinic drugs is preferable at a cold temperature to prevent degradation of the drugs and to extend their shelf life.
As indicated hereinbefore, generally, oral and nasal are the favourite sites of the administration but the composition can be applied to the rectal and vaginal mucosa. According to the physiologically active peptide or protein used, the dosage form and the site of administration a specific administration method can be selected.
The composition of this invention is generally prepared as microfine mixed micellar particles (1 to 10 nm or less) by the virtue of its preparation methods used and suitable combinations of absorption enhancer characteristics.
Administration of the formulation is by methods generally known in the art. For oral and nasal application, sprays are preferable, but also drops, chewable tablets, chewable gum and other suitable forms may be used. Utilization of atomizer or aerosol spray devices (metered dose inhalers or nebulizers) can be used to further reduce the particle size for effective inhalation from the nasal or oral cavity so the drug may successfully reach to the specific site and be absorbed. It is also possible to utilize a drug delivery system such that an enteric coating is applied to the gelatin capsule to cause the micelles to be released only in the duodenum or in the proximity of the large intestine and not in the stomach.
The invention is illustrated by reference to the following examples.